Treatment of iron sulphide-bearing material



July 11, 1933. R. F. BACON ET AL 1,917,228

TREATMENT 0F IRON SULPHIDE BEARING MATERIAL Filed Feb. 26, 1950 Fay/wond 7c. 5000/? ./'Saac .5e/76044072 ATTQRNEYS CLU Patented July 11', 17933 UiTED STATES PATENT OFFICE RAYMOND E. BACON, OF BRONXVILLE, AND ISAAC BENCOWITZ, 0F NEW YORK, N. Y.; SAID BENCOWITZ ASSIGNOB T0 SAID BACON TREATMENT OF IRON SULLPHIDE-BEARING MATERIAL Application led February 26, 1930. Serial No. 431,462.

This invention relates to the recovery of sulphur and has for an object the provision of an improved process for recovering sulphur from heavy metal sulphide ores. More particularly, the invention contemplates the provision of an improved process for recovering sulphur from materials containing one or more sulphides of iron. The invention. further contemplates the provision of an improved process for treating heavy metal sulphide ores such, for example, as ore containing sulphides of iron, copper and nickel.

The process of the present invention involves the treatment of ore or other metallurgical raw materials or products containing pyrites or other sulphides of iron, alone or in combination with sulphides of other heavy metals such, for example, as copper and nickel, with sulphuryl chloride for the purpose of obtaining free sulphur and/or separating iron from the mass of material undergoing treatment.

ln carrying out a process in accordance with the present invention, a quantity of the material to be treated is subjected to the action of sulphuryl chloride under such conditions that free sulphur and ferrie chloride are produced and vaporized. The vaporize'd sulphurvis collected and the ferrie chloride is utilized for treating additional quantities of sulphide-bearing material to produce a product in which ferrous chloride is concentrated. rllhe ferrous chloride concentrate is subjected to the action of steam and air at an elevated temperature to produce hydrogen chloride which is treated to recover chlorine. The chlorine recovered is returned to the process.

The process may be conveniently conduct ed by passing the sulphide-bearing` material progressively through reaction Zones of different temperatures. According to the preferred process of the invention, the iron sul phidc-bearing material is tirst introduced into a reaction Zone of relatively high tem-y perature and passed progressively through reaction zones of lower temperatures. The process is so controlled that ferrous chloride is produced in the high temperature reaction rones and ferrie chloride is produced in the lower temperature reaction Zones. Elemental sulphur is produced and vaporized and the ferrie chloride produced is vaporized. The vaporized sulphur and ferric chloride are lcaused to pass over fresh or partially 5J convertedv sulphide-bearing material in the higher temperature reaction Zones, the sulphur vapor ultimately being collected as free sulphur, and the ferrie chloride reacting with sulphide compounds and being reduced to ferrous chloride.

The ferrous chloride concentrate is subjected to the action of air and steam to produce hydrogen chloride. The hydrogen chloride produced is dried and subjected to the action of air in the presence of a suitable catalyst to produce free chlorine.

During the course of the reaction between the sulphuryl chloride and the sulphides contained in the material being treated, sulphur dioxide gas is formed and passes out of the reaction chamber with the vaporized sulphur. The recovered chlorine is combined with the sulphur dioxide produced to regenerate sulphuryl chloride which is returned to the 7 process.

The chlorination process may be carried out in any suitable type of apparatus, but it is preferably carried out in a rotary reaction chamber in which a suitable temperature gradient is maintained and into which the sulphuryl chloride and iron sulphide-bearing material are introduced at appropriate points.

l'lheinvention will be better understood from a 4consideration of the accompanying lowsheet and the following description of a process involving the treatment of ore containing pyrites and sulphides of copper and nickel. f

The ore to be treated is introduced in a dry, hnely divided condition into the interior of a rotary reaction chamber having charg ing means at one end and discharging` means at the other end. An opening or passage to permit the outward passage of sulphur vapors and other gases is provided near the charging end.

VThe reaction between the sulphuryl chloride and heavy metal sulphides starts ata ino temperature of about QO C. and proceeds most rapidly at a temperature of about 500O (l. to 55,00 C. lt is, therefore, advisable to maintain a temperature of about 500O C. to 5500 C. in at least a portion of the reaction chamber. Such a temperature may loe maintained near the charging 'end portion of the reaction chamber to insure the passage of all issuing gases through a zone in which conditions are conducive toa complete reaction.

The temperature Within the reaction chamber is preferaloly so regulated that it grad-- ually increases from the normal. atmospheric ten'iperature at the charging end to a maximum temperature of ahout 5500 C. at a point about midway between the charging end and the longitudinal. center of the reaction chainber, and gradually decreases from the regioi'l of maximum temperature to about 300 C. at the discharge end. rlhe opening or passage for sulphur vapors is preferably located at apoint between the charging end of the chamber andthe region of maximum teinperature Where the ten'ipcrature Within the chamber is about @i500 C. or slightly lower.

rlhe ore, preferably ground to provide particles suliieiently small to pass a 1GO-mesh screen in order that intimate contact of the sulphuryl chloride with the sulphide compounds may be obtained, is introduced into the reaction chamber at the charging end. Sulphuryl chloride is introduced into the reaction chamber' at the discharge end. The sulphuryl chloride may be introduced into the reaction chamber as a liquid or as a gas. Liquid sulphuryl chloride will be vaporized immediately after its introduction.

rllhe chlorine process is conducted as a batch process, the discharge end of the chainber being closed. The ore may be fed to the chamber continuously until the desired concentration has been eected, or the ore may be fed to th-e reaction chamber until a predetermined amount has been introduced.

l/Vhen ore is first introduced into the ieaction chamber, no sulphuryl chloride is introduced until the ore reaches or passes the rone 'of maximum temperature. As the ore reaches the zone of maximum temperature, the sulphuryl chloride may be admitted, slowly at first, and in gradually increasing amounts as the ore and chlorinated material progress through the chamber. vSulphuryl chloride may be admitted at any desired maximum rate. The rate at Which sulphuryl chloride is admitted and the amount lof sulphuryl chloride admitted Will be determined by the iate of feeding` of ore intoY the reaction Zones and the amount of ore to be treated.

During the course of the process, the sulphuryl chloride iii-st reacts Withthe sulphides of iron, copper and nickel to produce sulphur dioxide, free sulphur, ferrous chloride and the chlorides of copper and nickel. rlhe free sulphur is vaporized and passes out of the reaction chamber with the sulphur dioxide to suitable collecting and condensing appa- 'ratus As the reaction chamber is rotated,

the ferrous chloride-bearing material moves gradually toward ythe discharge end and fresh ore is moved into the zone of maximum teinperature. As the ferrous chloride-bearing material moves toward the discharge end the sulphuryl chloride reacts with the ferrous chloride and oxidizes it to ferrie chloride. The ferric chloride produced is vaporized and the resulting vapor is swept along With the sulphuryl chloride toward the Zone of maximum temperature. The ferrie chloride comes into Contact with fresh or partially chlorinated sulphide-bearing material and is reduced to ferrous chloride.

The chlorination process is so conducted and controlled that iron compounds are substantially completely eliminated from the material in the discharge end portion of the reaction ch amber and ferrous chloride is concentrated in the adjoining portion of the rcaction chamber. rlhe material in the discharge end portion of the reaction chamber will consist substantially entirely of nickel and copper chlorides and gangue materials which may be present in the original ore.

When the ore is fed continuously during the course of a process, the admission of ore and sulphuryl chloride may be discontinued when the presence of considerable ferrie chloride in the issuing sulphur vapor indicates that insufficient fresh ore is being moved into the reaction Zones to react With the ferrie chloride produced, or when the operations have been conducted for a predetermined length of time.

V/hen the ore is fed to the reaction chamber only until a predetermined amount has been admitted, the admission of sulphuryl chloride may be discontinued when the last portion of the ore reaches the zone of maximum temperature. The process may be so conducted that satisfactory concentration will have been effected at that time.

ln the case of continuous feeding, at the completion of the chlorination treatment, the iroii-jfree material containing chlorides of copper and nickel will be segregated in the discharge end portion of the chamber, fresh or substantially unaltered ore Will be present in the portion of the reaction chamber between the charging end andthe zone of maximum temperaure, and the ferrous chloridebearing material Will be concentrated in the v intermediate portion of the reaction chamber.

Upon the completion of a chlorination process involving the'admission of a predetermined amount of ore, the iron-free material will be segregated in the discharge end portion of the reaction chamber, and the ferrous chloride-bearing material Will be concharged the ferrous chloride concentrate is speed of the hydrolysisbut also air oxidation which takes place. rIhe treat-` Cil being moved toward the discharge end. After the iron-free material has been discharged' and collected,'the ferrous chloride concentrate is discharged and collected separately. lV hen the ferrous chlorideconcentrate has been discharged, treatment of a fresh batch of ore is commenced. y

The ferrous chloride concentrateis treated with steam in order to produce hydrogen chloride and oxide of the iron by hydrolysis. Air isl admitted with the steam in order to assist the reaction by oxidationof the iron. The air and steam are preheated in order 'to assist in maintaining the mass at the desired reaction temperature.l

VThe hydrolysiswill take place at normal atmospheric temperatures, but the rate of reaction is too slow for practical purposes. Higher temperatures not only increase the assist in the ment of the ferrous chloride concentrate with air and steam may be carried out satisfactorily at a temperature of from 400 C. to 600o C. Ordinarily a reaction temperature of about 500 0 C. isV entirely satisfactory.

rihe treatment of the ferrous chloride concentrate With air and steam may be carried out convenientlyY in a rotary reaction chamber having charging means at'one end and discharging means at the opposite end'and which is so constructed and arranged that the material passes from the charging end to the discharge end during its rotation. The ferrous chloride concentrate and the air and steam are introduced into the reaction chamber at the charging end and the resulting ferric oxide andhydrogen chloride are removed from the reaction chamber at the discharge end. The ferric oxide and hydrogen chlorides are preferably removed through separate discharge outlets. If the hydrogen chloride gas leaving the chamber carries considerable amounts of entrained particles of ferrie oxide it may be"k desirable to provide a settling kchamber into which the ferricfoxide and vhydrogen chloride may be introduced from the reaction chamber. Such a chambershouldbe maintained at a sufiicientlyhigh temperature vent the ferrous chloride from -adhering to the walls of the chamber. Such means'. aid in stirring and grinding the ferrous chloride and ferrie oxidek as they pass through the reaction chamber. y

rl-he gases issuing from the reaction chamber contain hydrogen'chloride Vand water vapor and they are passed through a suitable drying apparatus,` such,v for example, as a packed tower having sulphuric acid trickling therethrough to separate the water vapor and produce dry hydrogen chloride.

The dry hydrogen chloride is introduced Y into a catalytic reaction chamber with one to seven times its volume of air, dependmgon the concentration of the hydrogen chloride y available. The air is preheated to a temperature above 4200 C. and preferably to a temperature between 520o C. and 530o C. If desired, the hydrogen chloride may also be preheated. Suflicient excess air to provide the necessary oxygen for combinmgfwith the hydrogen chloride in the catalytic reaction chamber may be introduced into the reaction chamber in whichthe ferrous chloride concentrate is treated for the production yof `hydrogenv chloride. The excess air 'will pass through the system and enter the catalytic reaction chamber-with the hydrogen chloride. Y .Y

The catalytic reaction chamber preferably consists of a tower, or a series of communieating towers packed with a material having a very large surface per u'nit o f volume such, for example, as pumice, brick, cinders andthe like. The packing material should be of such a nature that it will be inert to the reagents and the products of the reaction. The packing material is covered or impregnated with l the catalyst which may be one or more chlorides or sulphates of' metals such, for example, as copper and nickel. The salts may be applied as such directly to the packing materialor they may be formed in place as, for

example, by the action of hydrogen chloride on copper oxide which is distributed throughout the mass. Means are provided for renewing thecatalytic mass as its efliciency becomes reduced. For this purpose two towers or two series of communicating towers which may be used alternately are preferably provided.

A portion of the iron-free materials produced may be utilized as a catalytic mass or for providing a solution of-copper chloride for impregnating a porous mass to be used in the catalytic chamber.

yThe apparatus is preferably so constructed, vthat the mass' of catalyst-bearing material may bel maintained at a temperature of from 870 Gto l0()O C. The reaction between the hydrogen chloridevand the oxygen of the air is exothermicvr and it may be socontrolled as to permit the proper temperature to be maintained. The reaction will proceed at v temperatures as low as 2050 C., and the temperatures-'as high as 470 C. may be used advantageously.- 'lhe temperature at which the reaction 1s conducted will Ibe governed largely by the nature of the catalyst. The temperature employed should be sufficiently low that excessive volatilization o'l the catalyst is avoided. The reaction involved 1n this operation does not proceed to completion. The issuingfrom the reaction chamberwvill consistof a mixture ofhydro- ,fren chloride, Water vapor and chlorine.

'i J. L JJ J. .4.1

ln View ol the iact that the-reaction does not readily proceed to completion, 1t may be desirable to retreat the issuing gases by subjecting them to a drying operation to remov the water vapor and subsequently pass- Aiugtheni through a second reaction chamber.

rl-his procedure may be repeated tivororthree or more times ii; desired. ln carrying out the reaction between hydrogen chloride and the oxygen cutairit. isadvisable to rcarefully control the propm'tions ol' air and hydrogen chloride utilized inorder to avoid es: aessive dilution oit the 'resulting chlorine The gases containingY hydrogen chloride and chlorine are Washed With Water to separateY the chlorine and hydrogen chloride. l` he resulting solution of hydrogen chloride in water may be treated in any suitable manner to recoverthe hydrogen chloride'.

. lhe chlorinerecovered is combined with the sulphur dioxide produced to regenerate sulphuryl chloride. The reaction between the sulphur dioxide and the tree chlorine `is prcterably conducted at or below normal atinospheric temperatures in the presence ot a suitable catalyst such, lor example, as activated charcoal. The regenerated sulphur-yl chloride may thus be obtained in the form of a liquid. The regenerated sulphuryl chloride is utilized for the treatment ofthe fresh batch of ore. Y

As a result of the treatment of the'ferrous chloride-hearing material and the hydrogen chloride with air, considerable quantities of inert gases such as nitrogen are introduced into the Vsystem and must be eliminated to avoid ,excessive dilution. The inert gases introd-.need into the system Will be mixed With the ,chlorine Y gas Which is recovered and which is combined with the sulphur dioxide produced to regenerate sulphuryl chloride. These gases -will be eliminated as a result of the production et liquid sulphuryl chloride. he inert gases may be passed through a suitable separator to par globiiles of sulphuryl chloride. j The. treatment ot a batch ot ore Withsulphuryl chloride and the treatment of a lierrous chloride-bearing residue for the recovery of chlorineare preferably conducted simultaneously in order that the sulphur dioxide and chlorine produced may be utilized "immediately. A fresh source-ot chlorine, in the free state or combined :in the form ot hydrogen chloride or sulphuryl chloride, may be recover entraineil` vaporize ler-ric, chloride, contacting said 'lierric chloride withlan additioiial portion of Asaid material to produce a 'ferrous chloride concentrate, subjecting the ferrous chloride concentrate to the action of steam and air at an elevatedtemperature to produce Yhydrogen chloride, treating the hydrogen chloride to recover chlorine, conve ing the chlorine to sulphur-yl chloride, and returningthe sulpluiryl chloride thus recovered to the process.

2. rthe method oit-'treating ironsujlphidebearing material which comprises subjecting the material .in a reaction chamber to the action oit sulphuryl chloride to produce and vaporize ieri-ic chloride, contacting said ilere lll ric chloride with an additional portion olf said material to produce a ferrous chloride concentrate, treating' the ferrous chloride concentrate to produce hydrogen chloride, treating` the hydrogen chloride to recover chlorine, converting' the chlorine to sulphur-yl chloride andvreturning the sulphuryl chloride thus recovered to the process.

v3.,'l`he 'method of'treatingore containing` sulphides of iron' and coppernvvhich comprises subjecting the ore to the action of sulphuryl chloride at an elevated temperature to obtain a product containing` copperv chloride and ferrous chloride subjecting the chloride product to the act-ion of additional sulphuryl chloride to convert the ferrous chloride to ferrie chloride, volatilizing the ferrie chloride yto leave a substantially ironree product containing` the copper chloride, contacting the ferrie chloride with the ore to obtain a -'ferrous chloride concentrate, treating' the ferrous chloride concentrate to produce hydrogenf chloride, treating the hydrogen chloride to recoverehlorine, convertini;` the chlorine 'to sulphuryl chloride, and returning` the sulphur-yl i covered to the process. l Y Y.

4l. rlhe method of treating ore containing' pyrites and a non-ferrous metal sulphide Which comprises subjecting' .the oreV to the action olf sulphuryl chloride to'obtain nonvferrous nietalchloride and lerrouschloride, subjecting the chloride productto the action et additional sulphnrylfchloridetoconvert the ferrous chloride to lerricehloride,*volatilizmg; the ferrie 'chloride toleave substanchloride thus Y. re.

chloride with the ore to obtain a ferrous chloride concentrate, treating the ferrous chloride concentrate to produce hydrogen chloride, treating the hydrogen chloride to recover chlorine, converting the chlorine to sulphuryl chloride and returning the sulphuryl chloride thus recovered to the process.

5. rlihe method of treating ore containing pyrites and sulphides of copper and nickel which comprises subjecting one portion of a charge of said ore to the action of sulphuryl chloride to form vapors of ferrieL chloride and elemental sulphur in the presence of sulphur dioxide and obtain substantially ironfree product containing copper and niclrel chlorides, and contacting the ferrie chloride Y with another portion of said charge to form a concentrate of solid ferrous chloride and liberate elemental sulphur as vapor.

6. The method of treating iron sulphidebearing material which comprises subjecting the material in a reaction chamber to the action of sulphuryl chloride to produce and vaporize ferrie chloride, contacting the ferric chloride so produced With another less chlorinated portion of said material to obtain a concentrate of solid ferrous chloride, treating the ferrous chloride concentrate to form hydrogen chloride, subjecting the hydrogen chloride to the action of oxygen in the presence of a portion of the iron-free product to recover chlorine, converting the chlorine to sulphuryl chloride and returning the sulphuryl chloride thus recovered to the process.

7. The method of treating iron sulphidebearing material which comprises, confining the material in a reaction chamber, chlorinating said material in one portion of said chamber to convert the iron to ferrous chloride, contacting the ferrous chloride so obtained with sulphuryl chloride to convert the ferrous chloride to ferrie chloride, Vaporizing said ferric chloride, and contacting said ferrie chloride and sulphuryl chloride with less chlorinated material in another portion of the chamber to further chlorinate the same and form a ferrous chloride concentrate with the liberation of elemental sulphur dioxide.

8. The method of treating iron sulphidebearing material Which comprises, contacting sulphuryl chloride With said material to chlorinate the same at temperatures Which are progressively increased as less chlorinated portions of the iron sulphide-bearing material come in contact with chlorinating agent.

9. The method of treating iron sulphidebearing material which comprises, chlorinating the material to produce ferrous chloride, subjecting the ferrous chloride to the action of sulphuryl chloride at a relatively loW temperature to produce and vaporize ferrie chloride, and subjecting the iron sulphide-bearing material to the action of said ferrie chloride vapor at a relatively high temperature to obtain a ferrous chloride concentrate.

In testimony whereof We aii'ix our signatures.

RAYMOND r. BACON. rsAAc BnNcoWiTZ.

@feminisme e1? nennne'non'.

111111111110. 1,917,228. Juny 11, 1933.

RAYMOND e. einen, E1 AL.

it is hereby certie that errer appears in the printed specification of the above numbered patent requiring ee'eetien es eiiows: Page 5, line 77, claim -7, after "sulphur" insert "in the presence o suiphur"; and that the said Letters Patent shnuid be read with this correction therein that the same may conform t0 the record of the case in the Patent ffice.

Signed and sealed'ths 24th day 0f October, A. D. 1933..

F. M. Hopkins (Seal.) Acting Commissioner of Patents. 

